Combination drill and countersink



April 30, 1929. BRANDT 1,711,012

COMBINATION DRILL AND COUNTERSINK Filed larch 30, 1925 gngnnto c i000; PH fimmor Patented Apr. 30, 1929.

UNITED" STA RUDOLPH BRANDT, OF SAN I The present ments in TES PATENT OFFICE.

BANCISGO, CALIFORNIA, .ASSIGNOR TO PE'IBY & BRANDT OF SAN FRANCISCO, CALIFORNIA, A COPARTNERSHIP.

COMBINATION DRILL AND GOUNTERSINKF Application filed March 30, 1925. Serial No. 19,331.

invention relates to improvea combination drill and countersink.

The drill to be, described in the present application is intended to be used in connection drilling with the drilling of brake linings and its principal. features are the incorporation of a portion, a counter-sinking portion and a stop into one single-piece unit and to arrange the three portions 1n such a manner that the whole unit may be manufactured very economically.

Further objects and advantages of my device will appear as the specification proceeds. The preferred form of my invention is illustrated' m the accompanying drawing, in

which Figure 1 shows a side view of my combination drill and countersink. Figure 2 a top plan new of the same.

Figure 3 a side view t.

ken at right angles to that of Figure 1, and

Figure 4 a bottom plan view. lVhile I have shown only the preferred form of the invention, it should be understood that various changes or modifications may be made within the scope of the claim hereto attached without departing from the spirit of the invention- In its preferred form my drill 1 comprises a shank 2 adapted to be mounted in any suitable manner in a chuck, not shown in the drai'ving, having a reduced end portion 3 at one end thereofwith an enlargement 4 ad acent the said endportion and a second enlargement 6 forming a continuation of the first enlargement 4. A peripheral cut 7 is milled into the material so as to extend from the point of the reduced end through the two enlargementsinto that portion of the shank 2 below the enlargements,

formed to present one straight side 8 lying in a radial plane of the shank and one curved side 9 penetrating into the material rather deeply near the point of the drill and gradu ally decreasingin depth as it passes through the enlargements.

The two enlargements 8 and 9 form an angle somewhat less than 90.

The end face 11 of the reduced portion 39f the shank is pointed and formed to rise toward the straight side produce corresponding 8 of the cut so as to a cutting edge adjacent the out. A

end face 12 of the first enlargement is also formed to rise toward the straight side 8 oi /the 'cutso as to form a corthe said out being responding cutting edge, but the correspondmg iace 13 of the second enlargement 1s made to drop toward the straight side 8 of the cut as shown at 14 so that no cutting edge is prescntcd at this point, the form of the second e1 ilairgement rather tending to cause the same to slide over the material when the drill is revolved and to ascend any slight wave that may be thrown up in the flexible material ahead of the same due to the drilling action. In actual use when the drill is rotated, the reduced end drills into the material of the brake band by means of its cutting edge and after the reduced end has reached a depth sufiicient to allow the first enlargement to come in contact with the material, the said enlargement drills into the same and forms a larger hole to the depth of its penetration. When the material, due to the continuationof the process, is engaged by the second enlargement 6, no cutting edge is presented to the material and the slight curve at 14 causes the second enlargement to slide over the material and to thus form an effective stop to further penetration.

It is evident, of course, that instead of one cut two outs may be prov1ded,.as shown in the stop, one side of said groove being flat or providing a cutting edge in the drilling portion and the countersinking portion, the other side of said groove being curved and emerging from the tool at a. point beyond the stop, said groove performing of conveying the out material away from the tool and of providing a cutting e e for the drilling portion and the countersi ing portion.

RUDOLPH BRANDT.

It will be seen that this single-piecedrill drilling po1..ion a the double function 

